Field of the Invention
The present invention relates to an imaging device. Priority is claimed on Japanese Patent Application No. 2013-186472, filed Sep. 9, 2013, the content of which is incorporated herein by reference.
Description of Related Art
Recently, the number of pixels of a solid-state imaging device in an imaging device such as a digital camera has increased year by year according to an increase in resolution of images to be captured. In general, the solid-state imaging device performs raster scanning and sequentially outputs signals (hereinafter referred to as “pixel signals”) of pixels in a horizontal direction (lateral direction) for an image. Because of this, in the image processing device provided in the imaging device and configured to process an image output by the solid-state imaging device, a storage capacity of the line memory for temporarily storing pixel signals of the horizontal direction output by the solid-state imaging device in a number of rows necessary for image processing also increases. An increase in the storage capacity of the line memory in the image processing device is a factor which increases a circuit scale of the imaging device.
For example, as in the publication of Japanese Patent No. 4179701, technology of the image processing device for performing image processing on one image through a plurality of separate operations is disclosed. In the technology disclosed in the publication of Japanese Patent No. 4179701, a pixel signal output from the solid-state imaging device is temporarily stored in a frame memory provided outside the image processing device and then one image is generated through a plurality of image processing operations while pixel signals necessary for the processing are read from the frame memory. For example, in the technology disclosed in the publication of Japanese Patent No. 4179701, as shown in FIG. 14A, the entire region of one image is divided into two regions, image processing is performed on one (left) half region in first image processing, and image processing is performed on the other (right) half region in the second image processing.
In the technology disclosed in the publication of Japanese Patent No. 4179701, one image is divided into a plurality of blocks and image processing is performed through operations equal in number to the division blocks, so that one image can be generated in the storage capacity of the line memory which is less than the number of pixels of the horizontal direction in which the solid-state imaging device performs an output operation.
In a pixel unit of a solid-state imaging device provided in an imaging device, there is an optical black region (hereinafter referred to as an “OB region”) of a plurality of columns or rows arranged on an end of an image region and constantly shielded. In photographing in the imaging device, image processing (hereinafter referred to as “black level correction”) for correcting a change in a black level represented by a pixel signal output by each pixel within the image region is performed based on a signal (hereinafter referred to as an “OB pixel signal”) of a pixel of the OB region. In general, in the pixel unit of the solid-state imaging device, the OB region includes a sub OB region of a horizontal direction (hereinafter referred to as an “HOB region”) and a sub OB region of a vertical direction (hereinafter referred to as a “VOB region”). The HOB region refers to a sub region in which a pixel located on either of the left and right of the image region and configured to output an OB pixel signal to be used for the black level correction of the horizontal direction of the image is arranged. The VOB region refers to a sub region in which in which a pixel located on either end of the top and bottom of the image region and configured to output an OB pixel signal to be used for the black level correction of the vertical direction (longitudinal direction) of the image is arranged. In FIG. 14B, an example of an image including an OB pixel signal output by a solid-state imaging device in which the HOB region is arranged on the left end of the image region and the VOB region is arranged on the upper end of the image region is shown.
The case in which the technology disclosed in the publication of Japanese Patent No. 4179701 is applied to the image and black level correction is performed by dividing the entire region of one image into two regions is considered. In this case, as shown in FIG. 14B, the HOB region is included in a left half region on which the black level correction is performed through a first operation, but no HOB region is included in a right half region on which the black level correction is performed in a second operation.
In addition, as disclosed in the publication of Japanese Unexamined Patent Application, First Publication No. 2009-094675, a solid-state imaging device with two HOB regions that are a HOB region corresponding to the image region of the left half and another HOB region corresponding to the image region of the right half is also implemented. In the solid-state imaging device of a configuration disclosed in the publication of Japanese Unexamined Patent Application, First Publication No. 2009-094675, it is possible to perform black level correction on each of the left and right regions even when the entire region of one image is divided into two regions.